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Karperien AL, Jelinek HF. Box-Counting Fractal Analysis: A Primer for the Clinician. ADVANCES IN NEUROBIOLOGY 2024; 36:15-55. [PMID: 38468026 DOI: 10.1007/978-3-031-47606-8_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
This chapter lays out the elementary principles of fractal geometry underpinning much of the rest of this book. It assumes a minimal mathematical background, defines the key principles and terms in context, and outlines the basics of a fractal analysis method known as box counting and how it is used to perform fractal, lacunarity, and multifractal analyses. As a standalone reference, this chapter grounds the reader to be able to understand, evaluate, and apply essential methods to appreciate and heal the exquisitely detailed fractal geometry of the brain.
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Affiliation(s)
| | - Herbert F Jelinek
- Department of Medical Sciences and Biotechnology Center, Khalifa University, Abu Dhabi, UAE
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2
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Yu L, Liu M, Li F, Wang Q, Wang M, So KF, Qu Y, Zhou L. Celsr2 Knockout Alleviates Inhibitory Synaptic Stripping and Benefits Motoneuron Survival and Axon Regeneration After Branchial Plexus Avulsion. Mol Neurobiol 2023; 60:1884-1900. [PMID: 36593433 PMCID: PMC9984348 DOI: 10.1007/s12035-022-03198-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/23/2022] [Indexed: 01/04/2023]
Abstract
Axotomy-induced synaptic stripping modulates survival and axon regeneration of injured motoneurons. Celsr2 is supposed to mediate homophilic interactions of neighboring cells during development, and its role in synaptic stripping remains unknow. In a model of brachial plexus avulsion, Celsr2 knockout improved functional recovery, motoneuron survival, and axon regeneration. Celsr2 was indicated to express in spinal motoneurons, excitatory and inhibitory interneurons, astrocytes, and a subset of oligodendrocytes using Celsr2LacZ mice. Double immunostaining showed that the coverage of inhibitory and excitatory vesicles on injured motoneurons were remarkably reduced after injury, whereas more inhibitory vesicles were maintained in Celsr2-/- mutants than control mice. In the ultrastructure, the density of inhibitory F-boutons on injured motoneurons was higher in Celsr2-/- mutants than controls. Conditional knockout of Celsr2 in astrocytes or oligodendrocytes showed the similar axotomy-induced synaptic withdrawal to the control. RNAseq of injured spinal samples identified 12 MHC I molecules with significant changes between Celsr2-/- and control mice. After injury, expression of MHC I surrounding injured motoneurons was increased, particularly high in Celsr2-/- mutants. In conclusion, Celsr2 knockout enhances MHC I signaling, alleviates inhibitory synaptic stripping cell-autonomously, and contributes to motoneuron survival and regeneration, and Celsr2 is a potential target for neural repair.
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Affiliation(s)
- Lingtai Yu
- Guangdong-Hongkong-Macau CNS Regeneration Institute of Jinan University, Key Laboratory of CNS Regeneration (Jinan University)-Ministry of Education, Guangzhou, 510632, People's Republic of China
| | - Mengfan Liu
- Guangdong-Hongkong-Macau CNS Regeneration Institute of Jinan University, Key Laboratory of CNS Regeneration (Jinan University)-Ministry of Education, Guangzhou, 510632, People's Republic of China
| | - Fuxiang Li
- Guangdong-Hongkong-Macau CNS Regeneration Institute of Jinan University, Key Laboratory of CNS Regeneration (Jinan University)-Ministry of Education, Guangzhou, 510632, People's Republic of China
| | - Qianghua Wang
- Guangdong-Hongkong-Macau CNS Regeneration Institute of Jinan University, Key Laboratory of CNS Regeneration (Jinan University)-Ministry of Education, Guangzhou, 510632, People's Republic of China
| | - Meizhi Wang
- Guangdong-Hongkong-Macau CNS Regeneration Institute of Jinan University, Key Laboratory of CNS Regeneration (Jinan University)-Ministry of Education, Guangzhou, 510632, People's Republic of China
| | - Kwok-Fai So
- Guangdong-Hongkong-Macau CNS Regeneration Institute of Jinan University, Key Laboratory of CNS Regeneration (Jinan University)-Ministry of Education, Guangzhou, 510632, People's Republic of China.,Department of Neurology and Stroke Center, The First Affiliated Hospital & Clinical Neuroscience Institute of Jinan University, Guangzhou, 510632, People's Republic of China.,Neuroscience and Neurorehabilitation Institute, University of Health and Rehabilitation Sciences, Qingdao, 266071, Shandong, People's Republic of China.,Co-Innovation Center of Neuroregeneration, Nantong University, Jiangsu, People's Republic of China
| | - Yibo Qu
- Guangdong-Hongkong-Macau CNS Regeneration Institute of Jinan University, Key Laboratory of CNS Regeneration (Jinan University)-Ministry of Education, Guangzhou, 510632, People's Republic of China.,Co-Innovation Center of Neuroregeneration, Nantong University, Jiangsu, People's Republic of China
| | - Libing Zhou
- Guangdong-Hongkong-Macau CNS Regeneration Institute of Jinan University, Key Laboratory of CNS Regeneration (Jinan University)-Ministry of Education, Guangzhou, 510632, People's Republic of China. .,Department of Neurology and Stroke Center, The First Affiliated Hospital & Clinical Neuroscience Institute of Jinan University, Guangzhou, 510632, People's Republic of China. .,Neuroscience and Neurorehabilitation Institute, University of Health and Rehabilitation Sciences, Qingdao, 266071, Shandong, People's Republic of China. .,Co-Innovation Center of Neuroregeneration, Nantong University, Jiangsu, People's Republic of China.
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3
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Events Occurring in the Axotomized Facial Nucleus. Cells 2022; 11:cells11132068. [PMID: 35805151 PMCID: PMC9266054 DOI: 10.3390/cells11132068] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 06/26/2022] [Accepted: 06/27/2022] [Indexed: 01/27/2023] Open
Abstract
Transection of the rat facial nerve leads to a variety of alterations not only in motoneurons, but also in glial cells and inhibitory neurons in the ipsilateral facial nucleus. In injured motoneurons, the levels of energy metabolism-related molecules are elevated, while those of neurofunction-related molecules are decreased. In tandem with these motoneuron changes, microglia are activated and start to proliferate around injured motoneurons, and astrocytes become activated for a long period without mitosis. Inhibitory GABAergic neurons reduce the levels of neurofunction-related molecules. These facts indicate that injured motoneurons somehow closely interact with glial cells and inhibitory neurons. At the same time, these events allow us to predict the occurrence of tissue remodeling in the axotomized facial nucleus. This review summarizes the events occurring in the axotomized facial nucleus and the cellular and molecular mechanisms associated with each event.
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4
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D'Agnelli S, Amodeo G, Franchi S, Verduci B, Baciarello M, Panerai AE, Bignami EG, Sacerdote P. Frailty and pain, human studies and animal models. Ageing Res Rev 2022; 73:101515. [PMID: 34813977 DOI: 10.1016/j.arr.2021.101515] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 11/08/2021] [Accepted: 11/11/2021] [Indexed: 11/01/2022]
Abstract
The hypothesis that pain can predispose to frailty development has been recently investigated in several clinical studies suggesting that frailty and pain may share some mechanisms. Both pain and frailty represent important clinical and social problems and both lack a successful treatment. This circumstance is mainly due to the absence of in-depth knowledge of their pathological mechanisms. Evidence of shared pathways between frailty and pain are preliminary. Indeed, many clinical studies are observational and the impact of pain treatment, and relative pain-relief, on frailty onset and progression has never been investigated. Furthermore, preclinical research on this topic has yet to be performed. Specific researches on the pain-frailty relation are needed. In this narrative review, we will attempt to point out the most relevant findings present in both clinical and preclinical literature on the topic, with particular attention to genetics, epigenetics and inflammation, in order to underline the existing gaps and the potential future interventional strategies. The use of pain and frailty animal models discussed in this review might contribute to research in this area.
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Krukowski K, Nolan A, Becker M, Picard K, Vernoux N, Frias ES, Feng X, Tremblay ME, Rosi S. Novel microglia-mediated mechanisms underlying synaptic loss and cognitive impairment after traumatic brain injury. Brain Behav Immun 2021; 98:122-135. [PMID: 34403733 PMCID: PMC9119574 DOI: 10.1016/j.bbi.2021.08.210] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 08/03/2021] [Accepted: 08/06/2021] [Indexed: 12/30/2022] Open
Abstract
Traumatic brain injury (TBI) is one of the leading causes of long-term neurological disability in the world. Currently, there are no therapeutics for treating the deleterious consequences of brain trauma; this is in part due to a lack of complete understanding of cellular processes that underlie TBI-related pathologies. Following TBI, microglia, the brain resident immune cells, turn into a "reactive" state characterized by the production of inflammatory mediators that contribute to the development of cognitive deficits. Utilizing multimodal, state-of-the-art techniques that widely span from ultrastructural analysis to optogenetic interrogation of circuit function, we investigated the reactive microglia phenotype one week after injury when learning and memory deficits are also measured. Microglia displayed increased: (i) phagocytic activity in vivo, (ii) synaptic engulfment, (iii) increased neuronal contact, including with dendrites and somata (termed 'satellite microglia'). Functionally, satellite microglia might impact somatic inhibition as demonstrated by the associated reduction in inhibitory synaptic drive. Cumulatively, here we demonstrate novel microglia-mediated mechanisms that may contribute to synaptic loss and cognitive impairment after traumatic brain injury.
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Affiliation(s)
- Karen Krukowski
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA, Brain and Spinal Injury Center, University of California, San Francisco, CA, USA
| | - Amber Nolan
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA, Brain and Spinal Injury Center, University of California, San Francisco, CA, USA
| | - McKenna Becker
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA, Brain and Spinal Injury Center, University of California, San Francisco, CA, USA
| | - Katherine Picard
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Nathalie Vernoux
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Elma S. Frias
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA, Brain and Spinal Injury Center, University of California, San Francisco, CA, USA, Department of Biomedical Sciences, University of California, San Francisco, CA, USA
| | - Xi Feng
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA, Brain and Spinal Injury Center, University of California, San Francisco, CA, USA
| | - Marie-Eve Tremblay
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada; Molecular Medicine Department, Université Laval, Québec, QC, Canada; Division of Medical Sciences, University of Victoria, Victoria, BC, Canada; Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada.
| | - Susanna Rosi
- Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, CA, USA; Brain and Spinal Injury Center, University of California, San Francisco, CA, USA; Department of Biomedical Sciences, University of California, San Francisco, CA, USA; Department of Neurological Surgery, University of California, San Francisco, CA, USA; Weill Institute for Neuroscience, University of California San Francisco, CA, USA; Kavli Institute of Fundamental Neuroscience, University of California San Francisco, CA, USA.
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6
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Nishihara T, Tanaka J, Sekiya K, Nishikawa Y, Abe N, Hamada T, Kitamura S, Ikemune K, Ochi S, Choudhury ME, Yano H, Yorozuya T. Chronic constriction injury of the sciatic nerve in rats causes different activation modes of microglia between the anterior and posterior horns of the spinal cord. Neurochem Int 2020; 134:104672. [PMID: 31926989 DOI: 10.1016/j.neuint.2020.104672] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 12/28/2019] [Accepted: 01/06/2020] [Indexed: 01/20/2023]
Abstract
Chronic constriction injury of the sciatic nerve is frequently considered as a cause of chronic neuropathic pain. Marked activation of microglia in the posterior horn (PH) has been well established with regard to this pain. However, microglial activation in the anterior horn (AH) is also strongly induced in this process. Therefore, in this study, we compared the differential activation modes of microglia in the AH and PH of the lumbar cord 7 days after chronic constriction injury of the left sciatic nerve in Wistar rats. Microglia in both the ipsilateral AH and PH demonstrated increased immunoreactivity of the microglial markers Iba1 and CD11b. Moreover, abundant CD68+ phagosomes were observed in the cytoplasm. Microglia in the AH displayed elongated somata with tightly surrounding motoneurons, whereas cells in the PH displayed a rather ameboid morphology and were attached to myelin sheaths rather than to neurons. Microglia in the AH strongly expressed NG2 chondroitin sulfate proteoglycan. Despite the tight attachment to neurons in the AH, a reduction in synaptic proteins was not evident, suggesting engagement of the activated microglia in synaptic stripping. Myelin basic protein immunoreactivity was observed in the phagosomes of activated microglia in the PH, suggesting the phagocytic removal of myelin. CCI caused both motor deficit and hyperalgesia that were evaluated by applying BBB locomotor rating scale and von Frey test, respectively. Motor defict was the most evident at postoperative day1, and that became less significant thereafter. By contrast, hyperalgesia was not severe at day 1 but it became worse at least by day 7. Collectively, the activation modes of microglia were different between the AH and PH, which may be associated with the difference in the course of motor and sensory symptoms.
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Affiliation(s)
- Tasuku Nishihara
- Department of Anesthesia and Perioperative Medicine, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
| | - Junya Tanaka
- Department of Molecular and Cellular Physiology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
| | - Keisuke Sekiya
- Department of Anesthesia and Perioperative Medicine, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
| | - Yuki Nishikawa
- Department of Anesthesia and Perioperative Medicine, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan; Department of Molecular and Cellular Physiology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
| | - Naoki Abe
- Department of Anesthesia and Perioperative Medicine, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
| | - Taisuke Hamada
- Department of Anesthesia and Perioperative Medicine, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
| | - Sakiko Kitamura
- Department of Anesthesia and Perioperative Medicine, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
| | - Keizo Ikemune
- Department of Anesthesia and Perioperative Medicine, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
| | - Shinichiro Ochi
- Department of Neuropsychiatry, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
| | - Mohammed E Choudhury
- Department of Molecular and Cellular Physiology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
| | - Hajime Yano
- Department of Molecular and Cellular Physiology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
| | - Toshihiro Yorozuya
- Department of Anesthesia and Perioperative Medicine, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
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Spinal Motor Circuit Synaptic Plasticity after Peripheral Nerve Injury Depends on Microglia Activation and a CCR2 Mechanism. J Neurosci 2019; 39:3412-3433. [PMID: 30833511 DOI: 10.1523/jneurosci.2945-17.2019] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 02/03/2019] [Accepted: 02/27/2019] [Indexed: 12/24/2022] Open
Abstract
Peripheral nerve injury results in persistent motor deficits, even after the nerve regenerates and muscles are reinnervated. This lack of functional recovery is partly explained by brain and spinal cord circuit alterations triggered by the injury, but the mechanisms are generally unknown. One example of this plasticity is the die-back in the spinal cord ventral horn of the projections of proprioceptive axons mediating the stretch reflex (Ia afferents). Consequently, Ia information about muscle length and dynamics is lost from ventral spinal circuits, degrading motor performance after nerve regeneration. Simultaneously, there is activation of microglia around the central projections of peripherally injured Ia afferents, suggesting a possible causal relationship between neuroinflammation and Ia axon removal. Therefore, we used mice (both sexes) that allow visualization of microglia (CX3CR1-GFP) and infiltrating peripheral myeloid cells (CCR2-RFP) and related changes in these cells to Ia synaptic losses (identified by VGLUT1 content) on retrogradely labeled motoneurons. Microgliosis around axotomized motoneurons starts and peaks within 2 weeks after nerve transection. Thereafter, this region becomes infiltrated by CCR2 cells, and VGLUT1 synapses are lost in parallel. Immunohistochemistry, flow cytometry, and genetic lineage tracing showed that infiltrating CCR2 cells include T cells, dendritic cells, and monocytes, the latter differentiating into tissue macrophages. VGLUT1 synapses were rescued after attenuating the ventral microglial reaction by removal of colony stimulating factor 1 from motoneurons or in CCR2 global KOs. Thus, both activation of ventral microglia and a CCR2-dependent mechanism are necessary for removal of VGLUT1 synapses and alterations in Ia-circuit function following nerve injuries.SIGNIFICANCE STATEMENT Synaptic plasticity and reorganization of essential motor circuits after a peripheral nerve injury can result in permanent motor deficits due to the removal of sensory Ia afferent synapses from the spinal cord ventral horn. Our data link this major circuit change with the neuroinflammatory reaction that occurs inside the spinal cord following injury to peripheral nerves. We describe that both activation of microglia and recruitment into the spinal cord of blood-derived myeloid cells are necessary for motor circuit synaptic plasticity. This study sheds new light into mechanisms that trigger major network plasticity in CNS regions removed from injury sites and that might prevent full recovery of function, even after successful regeneration.
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Assis AD, de Assis Araújo F, Dos Santos RAS, Andrade SP, Zanon RG. Pattern of Mas expression in acute and post-acute stage of nerve injury in mice. Peptides 2017; 96:15-19. [PMID: 28870798 DOI: 10.1016/j.peptides.2017.08.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 08/12/2017] [Accepted: 08/28/2017] [Indexed: 12/24/2022]
Abstract
Angiotensin-(1-7) (Ang [1-7]) and its receptor Mas are involved in a number of physiological processes, including control of arterial pressure and modulation of nervous system actions. However, the involvement of the Ang-(1-7)/Mas axis in peripheral nerve injury has not been investigated. Using a model of sciatic nerve injury in mice, we demonstrated opposing changes in Mas receptor expression at days 2 and 14 post-injury. Mas receptor expression was more intense 2days after the nerve lesion, compared with the intensity of the intact nerve. At this time point, the sciatic nerve functional index was -20. At day 14 after the lesion, the intensity of the immunostaining labeling in longitudinal sections of the nerve was reduced (∼30%) and the functional index increased +36 (gait improvement). In the axotomized group treated with A779 (a Mas receptor antagonist), the functional recovery index decreased in relation to the untreated axotomized group. The Mas receptor inhibitor also altered the intensity of labeling of S-100, GAP43, and IBA-1 (morphological features compatible with delayed axon growth). This study demonstrated that Ang-(1-7)/Mas axis activity was differentially modulated in the acute and post-acute stages of nerve injury.
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Affiliation(s)
- Alex Dias Assis
- Department of Human Anatomy, Institute of Biomedical Sciences, Federal University of Uberlandia (UFU), Uberlandia, MG, Brazil
| | - Fernanda de Assis Araújo
- Department of Physiology, Institute of Biomedical Sciences, Federal University of Uberlandia (UFU), Uberlandia, MG, Brazil
| | | | - Silvia Passos Andrade
- Department of Physiology, Federal University of Minas Gerais (UFMG), Belo Horizonte, MG, Brazil
| | - Renata Graciele Zanon
- Department of Human Anatomy, Institute of Biomedical Sciences, Federal University of Uberlandia (UFU), Uberlandia, MG, Brazil.
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9
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Karperien AL, Jelinek HF. Box-Counting Fractal Analysis: A Primer for the Clinician. SPRINGER SERIES IN COMPUTATIONAL NEUROSCIENCE 2016. [DOI: 10.1007/978-1-4939-3995-4_2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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10
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Olmstead DN, Mesnard-Hoaglin NA, Batka RJ, Haulcomb MM, Miller WM, Jones KJ. Facial nerve axotomy in mice: a model to study motoneuron response to injury. J Vis Exp 2015:e52382. [PMID: 25742324 DOI: 10.3791/52382] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The goal of this surgical protocol is to expose the facial nerve, which innervates the facial musculature, at its exit from the stylomastoid foramen and either cut or crush it to induce peripheral nerve injury. Advantages of this surgery are its simplicity, high reproducibility, and the lack of effect on vital functions or mobility from the subsequent facial paralysis, thus resulting in a relatively mild surgical outcome compared to other nerve injury models. A major advantage of using a cranial nerve injury model is that the motoneurons reside in a relatively homogenous population in the facial motor nucleus in the pons, simplifying the study of the motoneuron cell bodies. Because of the symmetrical nature of facial nerve innervation and the lack of crosstalk between the facial motor nuclei, the operation can be performed unilaterally with the unaxotomized side serving as a paired internal control. A variety of analyses can be performed postoperatively to assess the physiologic response, details of which are beyond the scope of this article. For example, recovery of muscle function can serve as a behavioral marker for reinnervation, or the motoneurons can be quantified to measure cell survival. Additionally, the motoneurons can be accurately captured using laser microdissection for molecular analysis. Because the facial nerve axotomy is minimally invasive and well tolerated, it can be utilized on a wide variety of genetically modified mice. Also, this surgery model can be used to analyze the effectiveness of peripheral nerve injury treatments. Facial nerve injury provides a means for investigating not only motoneurons, but also the responses of the central and peripheral glial microenvironment, immune system, and target musculature. The facial nerve injury model is a widely accepted peripheral nerve injury model that serves as a powerful tool for studying nerve injury and regeneration.
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Affiliation(s)
- Deborah N Olmstead
- Anatomy and Cell Biology, Indiana University School of Medicine; Research and Development Services, Richard L. Roudebush VA Medical Center
| | | | - Richard J Batka
- Anatomy and Cell Biology, Indiana University School of Medicine; Research and Development Services, Richard L. Roudebush VA Medical Center
| | - Melissa M Haulcomb
- Anatomy and Cell Biology, Indiana University School of Medicine; Research and Development Services, Richard L. Roudebush VA Medical Center
| | - Whitney M Miller
- Anatomy and Cell Biology, Indiana University School of Medicine; Research and Development Services, Richard L. Roudebush VA Medical Center
| | - Kathryn J Jones
- Anatomy and Cell Biology, Indiana University School of Medicine; Research and Development Services, Richard L. Roudebush VA Medical Center;
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11
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Villacampa N, Almolda B, Vilella A, Campbell IL, González B, Castellano B. Astrocyte-targeted production of IL-10 induces changes in microglial reactivity and reduces motor neuron death after facial nerve axotomy. Glia 2015; 63:1166-84. [PMID: 25691003 DOI: 10.1002/glia.22807] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 01/28/2015] [Indexed: 12/30/2022]
Abstract
Interleukin-10 (IL-10) is a cytokine that plays a crucial role in regulating the inflammatory response and immune reactions. In the central nervous system (CNS), IL-10 is mainly produced by astrocytes and microglia and it is upregulated after various insults, such as experimental autoimmune encephalomyelitis, middle cerebral artery occlusion, excitotoxicity and traumatic brain injury. To better understand the effects of IL-10 in the normal and injured CNS, we generated transgenic mice (termed GFAP-IL-10Tg) that expressed the murine IL-10 gene under the transcriptional control of the glial fibrillary acidic protein (GFAP) promoter. Previous studies demonstrated marked changes in the microglial phenotype in these mice under basal conditions. The objective of the present study was to investigate the effects of local astrocyte-targeted IL-10 production on glial activation, neuronal degeneration and leukocyte recruitment after axotomy. GFAP-IL-10Tg mice had marked changes in the phenotype of activated microglial cells, as well as in the number of microglial clusters and in microglial cell density. These microglial changes are accompanied by a twofold increase in lymphocyte infiltration in GFAP-IL-10Tg mice and around twofold decrease in neuronal cell death at 21 dpi. Altogether, our findings suggested that astrocyte-targeted production of IL-10 impacted the microglial response and lymphocyte recruitment and culminated in a beneficial effect on neuronal survival.
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Affiliation(s)
- Nàdia Villacampa
- Department of Cell Biology, Physiology and Immunology, Institute of Neuroscience, Universitat Autònoma de Barcelona, Bellaterra, 08193, Barcelona, Spain
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12
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Kobayashi M, Konishi H, Takai T, Kiyama H. A DAP12-dependent signal promotes pro-inflammatory polarization in microglia following nerve injury and exacerbates degeneration of injured neurons. Glia 2015; 63:1073-82. [PMID: 25690660 DOI: 10.1002/glia.22802] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 01/16/2015] [Indexed: 01/17/2023]
Abstract
Under pathological conditions, activated microglia play paradoxical roles and could have neurotoxic or neuroprotective effects. However, the signal determining how activated microglia affects the fate of neuronal cells remains largely unknown. Here we demonstrate that DNAX-activating protein of 12 kDa (DAP12), a transmembrane adaptor protein that contains an immunoreceptor tyrosine-based activation motif, is a critical regulator of microglial function after nerve injury. In a model of mouse hypoglossal nerve injury, the duration of microglial increase after nerve injury became shorter in mice lacking DAP12, although microglial morphology and total cell numbers were not significantly affected during early phase after nerve injury. Intriguingly, expressions of M1-phenotype markers including pro-inflammatory cytokines were suppressed in DAP12-deficient microglia. Furthermore, axotomy-induced motor neuron death was markedly prevented in DAP12-deficient mice. Collectively, DAP12-mediated microglial activation following axotomy promotes pro-inflammatory responses, and thereby accelerates nerve injury-induced neuron death, suggesting that DAP12 is a potential therapeutic target for the protection of neuronal degeneration caused by microglial activation.
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Affiliation(s)
- Masaaki Kobayashi
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, Nagoya, Japan
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13
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González-Forero D, Moreno-López B. Retrograde response in axotomized motoneurons: nitric oxide as a key player in triggering reversion toward a dedifferentiated phenotype. Neuroscience 2014; 283:138-65. [PMID: 25168733 DOI: 10.1016/j.neuroscience.2014.08.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 08/03/2014] [Accepted: 08/14/2014] [Indexed: 12/11/2022]
Abstract
The adult brain retains a considerable capacity to functionally reorganize its circuits, which mainly relies on the prevalence of three basic processes that confer plastic potential: synaptic plasticity, plastic changes in intrinsic excitability and, in certain central nervous system (CNS) regions, also neurogenesis. Experimental models of peripheral nerve injury have provided a useful paradigm for studying injury-induced mechanisms of central plasticity. In particular, axotomy of somatic motoneurons triggers a robust retrograde reaction in the CNS, characterized by the expression of plastic changes affecting motoneurons, their synaptic inputs and surrounding glia. Axotomized motoneurons undergo a reprograming of their gene expression and biosynthetic machineries which produce cell components required for axonal regrowth and lead them to resume a functionally dedifferentiated phenotype characterized by the removal of afferent synaptic contacts, atrophy of dendritic arbors and an enhanced somato-dendritic excitability. Although experimental research has provided valuable clues to unravel many basic aspects of this central response, we are still lacking detailed information on the cellular/molecular mechanisms underlying its expression. It becomes clear, however, that the state-switch must be orchestrated by motoneuron-derived signals produced under the direction of the re-activated growth program. Our group has identified the highly reactive gas nitric oxide (NO) as one of these signals, by providing robust evidence for its key role to induce synapse elimination and increases in intrinsic excitability following motor axon damage. We have elucidated operational principles of the NO-triggered downstream transduction pathways mediating each of these changes. Our findings further demonstrate that de novo NO synthesis is not only "necessary" but also "sufficient" to promote the expression of at least some of the features that reflect reversion toward a dedifferentiated state in axotomized adult motoneurons.
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Affiliation(s)
- D González-Forero
- Grupo de Neurodegeneración y Neuroreparación (GRUNEDERE), Área de Fisiología, Instituto de Biomoléculas (INBIO), Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.
| | - B Moreno-López
- Grupo de Neurodegeneración y Neuroreparación (GRUNEDERE), Área de Fisiología, Instituto de Biomoléculas (INBIO), Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.
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Mesnard-Hoaglin NA, Xin J, Haulcomb MM, Batka RJ, Sanders VM, Jones KJ. SOD1(G93A) transgenic mouse CD4(+) T cells mediate neuroprotection after facial nerve axotomy when removed from a suppressive peripheral microenvironment. Brain Behav Immun 2014; 40:55-60. [PMID: 24911596 PMCID: PMC4131730 DOI: 10.1016/j.bbi.2014.05.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 05/29/2014] [Accepted: 05/29/2014] [Indexed: 12/13/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease involving motoneuron (MN) axonal withdrawal and cell death. Previously, we established that facial MN (FMN) survival levels in the SOD1(G93A) transgenic mouse model of ALS are reduced and nerve regeneration is delayed, similar to immunodeficient RAG2(-/-) mice, after facial nerve axotomy. The objective of this study was to examine the functionality of SOD1(G93A) splenic microenvironment, focusing on CD4(+) T cells, with regard to defects in immune-mediated neuroprotection of injured MN. We utilized the RAG2(-/-) and SOD1(G93A) mouse models, along with the facial nerve axotomy paradigm and a variety of cellular adoptive transfers, to assess immune-mediated neuroprotection of FMN survival levels. We determined that adoptively transferred SOD1(G93A) unfractionated splenocytes into RAG2(-/-) mice were unable to support FMN survival after axotomy, but that adoptive transfer of isolated SOD1(G93A) CD4(+) T cells could. Although WT unfractionated splenocytes adoptively transferred into SOD1(G93A) mice were able to maintain FMN survival levels, WT CD4(+) T cells alone could not. Importantly, these results suggest that SOD1(G93A) CD4(+) T cells retain neuroprotective functionality when removed from a dysfunctional SOD1(G93A) peripheral splenic microenvironment. These results also indicate that the SOD1(G93A) central nervous system microenvironment is able to re-activate CD4(+) T cells for immune-mediated neuroprotection when a permissive peripheral microenvironment exists. We hypothesize that a suppressive SOD1(G93A) peripheral splenic microenvironment may compromise neuroprotective CD4(+) T cell activation and/or differentiation, which, in turn, results in impaired immune-mediated neuroprotection for MN survival after peripheral axotomy in SOD1(G93A) mice.
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Affiliation(s)
- Nichole A. Mesnard-Hoaglin
- Neuroscience Institute, Loyola University Medical Center, Maywood, IL 60153, USA,Research and Development Service, Hines VAMC, Hines, IL 60141, USA,Dept. of Anatomy and Cell Biology, Indiana University, Indianapolis, IN 46202, USA,Corresponding Authora: Nichole Mesnard-Hoaglin, Ph.D., Dept. of Anatomy & Cell Biology, Indiana University School of Medicine, 635 Barnhill Dr. MS-5025H, Indianapolis, IN, Lab: 317-278-2462,
| | - Junping Xin
- Neuroscience Institute, Loyola University Medical Center, Maywood, IL 60153, USA,Research and Development Service, Hines VAMC, Hines, IL 60141, USA
| | - Melissa M. Haulcomb
- Dept. of Anatomy and Cell Biology, Indiana University, Indianapolis, IN 46202, USA,Research and Development Service, Roudebush VAMC, Indianapolis, IN 46202, USA
| | - Richard J. Batka
- Dept. of Anatomy and Cell Biology, Indiana University, Indianapolis, IN 46202, USA,Research and Development Service, Roudebush VAMC, Indianapolis, IN 46202, USA
| | - Virginia M. Sanders
- Dept. of Molecular Virology, Immunology, and Medical Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Kathryn J. Jones
- Dept. of Anatomy and Cell Biology, Indiana University, Indianapolis, IN 46202, USA,Research and Development Service, Roudebush VAMC, Indianapolis, IN 46202, USA
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15
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Fuentes-Santamaría V, Alvarado JC, Gabaldón-Ull MC, Manuel Juiz J. Upregulation of insulin-like growth factor and interleukin 1β occurs in neurons but not in glial cells in the cochlear nucleus following cochlear ablation. J Comp Neurol 2014; 521:3478-99. [PMID: 23681983 DOI: 10.1002/cne.23362] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2013] [Revised: 04/30/2013] [Accepted: 05/03/2013] [Indexed: 12/30/2022]
Abstract
One of the main mechanisms used by neurons and glial cells to promote repair following brain injury is to upregulate activity-dependent molecules such as insulin-like growth factor 1 (IGF-1) and interleukin-1β (IL-1β). In the auditory system, IGF-1 is crucial for restoring synaptic transmission following hearing loss; however, whether IL-1β is also involved in this process is unknown. In this study, we evaluated the expression of IGF-1 and IL-1β within neurons and glial cells of the ventral cochlear nucleus in adult rats at 1, 7, 15, and 30 days following bilateral cochlear ablation. After the lesion, significant increases in both the overall mean gray levels of IGF-1 immunostaining and the mean gray levels within cells of the cochlear nucleus were observed at 1, 7, and 15 days compared with control animals. The expression and distribution of IL-1β in the ventral cochlear nucleus of ablated animals was temporally and spatially correlated with IGF-1. We also observed a lack of colocalization between IGF-1 and IL-1β with either astrocytes or microglia at any of the time points following ablation. These results suggest that the upregulation of IGF-1 and IL-1β levels within neurons-but not within glial cells-may reflect a plastic mechanism involved in repairing synaptic homeostasis of the overall cellular environment of the cochlear nucleus following bilateral cochlear ablation.
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Affiliation(s)
- Verónica Fuentes-Santamaría
- Institute for Research on Neurological Disorders (IDINE), Faculty of Medicine, University of Castilla-La Mancha, 02006, Albacete, Spain
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16
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Peters JH, Gallaher ZR, Ryu V, Czaja K. Withdrawal and restoration of central vagal afferents within the dorsal vagal complex following subdiaphragmatic vagotomy. J Comp Neurol 2014; 521:3584-99. [PMID: 23749657 DOI: 10.1002/cne.23374] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 04/19/2013] [Accepted: 05/23/2013] [Indexed: 12/21/2022]
Abstract
Vagotomy, a severing of the peripheral axons of the vagus nerve, has been extensively utilized to determine the role of vagal afferents in viscerosensory signaling. Vagotomy is also an unavoidable component of some bariatric surgeries. Although it is known that peripheral axons of the vagus nerve degenerate and then regenerate to a limited extent following vagotomy, very little is known about the response of central vagal afferents in the dorsal vagal complex to this type of damage. We tested the hypothesis that vagotomy results in the transient withdrawal of central vagal afferent terminals from their primary central target, the nucleus of the solitary tract (NTS). Sprague-Dawley rats underwent bilateral subdiaphragmatic vagotomy and were sacrificed 10, 30, or 60 days later. Plastic changes in vagal afferent fibers and synapses were investigated at the morphological and functional levels by using a combination of an anterograde tracer, synapse-specific markers, and patch-clamp electrophysiology in horizontal brain sections. Morphological data revealed that numbers of vagal afferent fibers and synapses in the NTS were significantly reduced 10 days following vagotomy and were restored to control levels by 30 days and 60 days, respectively. Electrophysiology revealed transient decreases in spontaneous glutamate release, glutamate release probability, and the number of primary afferent inputs. Our results demonstrate that subdiaphragmatic vagotomy triggers transient withdrawal and remodeling of central vagal afferent terminals in the NTS. The observed vagotomy-induced plasticity within this key feeding center of the brain may be partially responsible for the response of bariatric patients following gastric bypass surgery.
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Affiliation(s)
- James H Peters
- Program in Neuroscience, Integrative Physiology and Neuroscience (IPN), College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164
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17
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Microglia: actively surveying and shaping neuronal circuit structure and function. Trends Neurosci 2013; 36:209-17. [DOI: 10.1016/j.tins.2012.11.007] [Citation(s) in RCA: 332] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 11/16/2012] [Accepted: 11/17/2012] [Indexed: 11/17/2022]
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18
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Raslan A, Ernst P, Werle M, Thieme H, Szameit K, Finkensieper M, Guntinas-Lichius O, Irintchev A. Reduced cholinergic and glutamatergic synaptic input to regenerated motoneurons after facial nerve repair in rats: potential implications for recovery of motor function. Brain Struct Funct 2013; 219:891-909. [DOI: 10.1007/s00429-013-0542-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Accepted: 03/12/2013] [Indexed: 02/02/2023]
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19
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Karperien A, Ahammer H, Jelinek HF. Quantitating the subtleties of microglial morphology with fractal analysis. Front Cell Neurosci 2013; 7:3. [PMID: 23386810 PMCID: PMC3558688 DOI: 10.3389/fncel.2013.00003] [Citation(s) in RCA: 318] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 01/08/2013] [Indexed: 01/17/2023] Open
Abstract
It is well established that microglial form and function are inextricably linked. In recent years, the traditional view that microglial form ranges between “ramified resting” and “activated amoeboid” has been emphasized through advancing imaging techniques that point to microglial form being highly dynamic even within the currently accepted morphological categories. Moreover, microglia adopt meaningful intermediate forms between categories, with considerable crossover in function and varying morphologies as they cycle, migrate, wave, phagocytose, and extend and retract fine and gross processes. From a quantitative perspective, it is problematic to measure such variability using traditional methods, but one way of quantitating such detail is through fractal analysis. The techniques of fractal analysis have been used for quantitating microglial morphology, to categorize gross differences but also to differentiate subtle differences (e.g., amongst ramified cells). Multifractal analysis in particular is one technique of fractal analysis that may be useful for identifying intermediate forms. Here we review current trends and methods of fractal analysis, focusing on box counting analysis, including lacunarity and multifractal analysis, as applied to microglial morphology.
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Affiliation(s)
- Audrey Karperien
- Centre for Research in Complex Systems, School of Community Health, Charles Sturt University Albury, NSW, Australia
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Abstract
Broad interest in the rapidly advancing field of microglial involvement in forming neural circuits is evident from the fresh findings published in leading journals. This special issue of Neuron Glia Biology contains a special collection of research articles and reviews concerning the new appreciation of microglial function in the normal physiology of the brain that extends beyond their traditionally understood role in pathology.
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Yamada J, Jinno S. Upregulation of calcium binding protein, S100A6, in activated astrocytes is linked to glutamate toxicity. Neuroscience 2012; 226:119-29. [PMID: 22982625 DOI: 10.1016/j.neuroscience.2012.08.068] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 08/29/2012] [Accepted: 08/31/2012] [Indexed: 10/27/2022]
Abstract
S100A6 (calcyclin), an EF-hand calcium binding protein, is considered to exert various functions, e.g., cell proliferation and differentiation, calcium homeostasis, and neuronal degeneration. In this study, we aimed to investigate whether S100A6 might be linked to glutamate toxicity using three animal models and pharmacological interventions. We first examined the age-related changes in S100A6 immunoreactivity in the mouse hippocampus, considering that an important negative aspect of brain aging is linked to increased extracellular glutamate. The surface area of S100A6-positive (+) astrocytes was significantly larger in aged mice than in young mice, while the numbers of S100β+ astrocytes did not change with age. In the second experiment, we examined the alterations in S100A6 immunoreactivity in the injured hypoglossal nucleus, because glutamate toxicity is considered to contribute to neuronal death after axotomy. There was no apparent S100A6 immunoreactivity in the hypoglossal nucleus of sham control animals. However, intense labeling for S100A6 in activated astrocytes was observed in the axotomized hypoglossal nucleus of mice. Administration of ceftriaxone, an astrocyte glutamate transporter enhancer, to axotomized mice significantly decreased the immunoreactivity for S100A6. In the third experiment, we tested an animal model of epilepsy using kainic acid (KA), a glutamate analog. In the mouse hippocampus after KA injection, S100A6 immunoreactivity was significantly increased in astrocytes, and pyknotic changes were observed in CA3 pyramidal neurons. Treatment of MK-801, an N-methyl-d-aspartate receptor antagonist, counteracted the KA-induced increase in S100A6 immunoreactivity, and reduced the numbers of pyknotic neurons. Our results indicate that upregulation of astrocytic S100A6 in response to extracellular glutamate may be involved in neuronal damage under pathophysiological conditions.
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Affiliation(s)
- J Yamada
- Department of Developmental Molecular Anatomy, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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